took place. any other photographs will be compared against those two explosion sites, number one, to see if a bag had been there. number two, we'll be looking for someone who carried such a bag. remember, al, that the fbi describes two different black nylon bags. if you think about -- if you think about these pressure cookers, a friend of mine, larry johnson, former cia, commented that these would weigh about 20 pounds each. that's a lot of weight for somebody to carry in that area, al. >> now, what kind of damage can these type of bombs do, these pressure cooker bombs? >> well, let's say, for example, in february of this year, a pressure cooker bomb was used in india, with us set off. 17 dead, 120 injured. in july 1976, a hijacking took place in america.